The skeleton oil seal is a typical representative of an oil seal. Generally speaking, an oil seal refers to a skeleton oil seal. The role of the oil seal is generally to isolate the components that need to be lubricated from the output components in the transmission components, so as not to let the lubricant leak. The skeleton is like the steel bar in the concrete member, which plays a role of strengthening and makes the oil seal maintain the shape and tension. According to the structure, it can be divided into single lip skeleton oil seal and double lip skeleton oil seal. The auxiliary lip of the double lip skeleton oil seal plays a dustproof role, preventing outside dust and impurities from entering the machine. According to the frame type, it can be divided into inner frame oil seal, exposed frame oil seal and assembled oil seal. According to working conditions, it can be divided into rotary skeleton oil seal and round-trip skeleton oil seal. Used in gasoline engine crankshaft, diesel engine crankshaft, gearbox, differential, shock absorber, engine, axle and other parts.
Skeleton oil seal structure consists of three parts: oil seal body, reinforced skeleton and self-tightening coil spring. The sealing body is divided into bottom part, waist frame oil seal structure drawing part, cutting edge and sealing lip according to different parts. Generally, the skeleton oil seal in a free state has an inner diameter smaller than the shaft diameter, that is, it has a certain amount of interference. Therefore, after the oil is encapsulated in the oil seal seat and the shaft, the pressure of the oil seal blade and the contraction force of the self-tightening coil spring produce a certain radial tension on the shaft. After a period of operation, the pressure will quickly decrease or disappear Therefore, the spring can compensate the self-tightening force of the oil seal at any time.
Sealing principle: Because there is an oil film controlled by the oil seal cutting edge between the oil seal and the shaft, this oil film has fluid lubrication characteristics.
Under the effect of the skeleton oil seal, the rigidity of the oil film just makes the oil film and the air contact end form a crescent surface, which prevents the leakage of the working medium and thus realizes the sealing of the rotating shaft. The sealing ability of the oil seal depends on the thickness of the oil film on the sealing surface. If the thickness is too large, the oil seal may leak. If the thickness is too small, dry friction may occur, which may cause wear of the oil seal and the shaft. . Therefore, during installation, you must apply some oil to the seal ring, and at the same time ensure that the skeleton oil seal is perpendicular to the axis of the shaft. If it is not vertical, the seal lip of the oil seal will drain the lubricant from the shaft, and it will cause excessive sealing lip. Wear. During operation, the lubricant in the casing slightly oozes out a little, so as to achieve the state of forming an oil film on the sealing surface.
The role of skeleton oil seal is generally to isolate the parts that need to be lubricated from the output parts in the transmission parts, so as not to let the lubricant leak, it is usually used for the rotating shaft, which is a rotating shaft lip seal. The skeleton is like the steel bar in the concrete member, which plays a role of strengthening and makes the oil seal maintain the shape and tension. According to the frame type, it can be divided into inner frame oil seal, outer frame oil seal, and inner and outer frame oil seal. The skeleton oil seal is made of high-quality nitrile rubber and steel plate, with stable quality and long service life. Widely used in automobile, motorcycle crankshaft, camshaft, differential, shock absorber, engine, axle, front and rear wheels and other parts.
1. Prevent mud, dust, moisture, etc. from intruding into the bearing from the outside;
2. Limit the leakage of lubricating oil in the bearing. The requirements for oil seals are that the dimensions (inner diameter, outer diameter, and thickness) should meet the requirements; it requires appropriate elasticity, which can properly lock the shaft and play a sealing role; it must be heat-resistant, wear-resistant, good strength, and medium-resistant ( Oil or water, etc.), long service life.
Fair use of oil seals should pay attention to the following points:
(1) Shaft speed Due to design and structural reasons, high-speed oil seals should be used for high-speed shafts, and low-speed oil seals should be used for low-speed shafts. Low-speed oil seals cannot be used on high-speed shafts, and vice versa.
(2) When the ambient temperature is high, use polypropylene ester or silicon, fluorine, silicon-fluorine rubber. And should try to reduce the oil temperature in the oil tank. When the temperature is too low, cold-resistant rubber should be used.
(3) The oil seal with normal pressure is poor in withstand pressure. When the pressure is too large, the oil seal will be deformed. Under the conditions of excessive pressure, a pressure-resistant support ring or a reinforced pressure-resistant oil seal should be used.
(4) The degree of eccentricity of the installation is too large when the oil seal and the shaft are fitted, the sealing performance will deteriorate, especially when the shaft speed is high. If the eccentricity is too large, a W-shaped oil seal can be used.
(5) The surface finish of the shaft directly affects the service life of the oil seal. That is, if the shaft finish is high, the service life of the oil seal will be long.
(6) Note that there should be a certain amount of lubricating oil in the lip of the oil seal.
(7) Pay special attention to prevent dust from entering the oil seal.
Skeleton oil seals are widely used in aviation, automobiles, motorcycles, railways, vehicles, ships, home appliances, construction machinery and other industries. Suitable for rotary motion and reciprocating motion sealing. Installed in various types of engines, gearboxes, axles, ships, cylinders and other parts. Mainly to prevent the penetration of the sealed medium (gas. liquid.) and external foreign matter into the body.
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